Hitherto, a device for inspecting a defect in one side of a cloth has been proposed which inspects the surface of the cloth that is spread over a belt and is moved together with the belt to be folded after being washed with water, dried and ironed. The proposed device automatically inspects a defect, such as a damage and dirt, in one side of the cloth by illuminating light to the one side of the cloth, capturing the light reflecting from the one side of the cloth by a camera or the like, converting the intensity of light of an image captured by the camera or the like (the intensity of light reflecting from a defective portion is relatively weak) to an electric signal, and processing the converted electric signal. (See Patent Document 1)
Also, there is known a method of, in that type of inspecting device, comparing the converted electric signal with a regular pattern program that is stored in advance, and canceling a pattern signal from the converted electric signal, thus selecting only a signal representing a defect of the cloth (see Patent Document 2).
With the known device, however, because the timings of starting and ending the inspection are adjusted by using sensors to detect the presence of the cloth, problems arise in the following points. An operation failure is caused in the event of malfunction of sensors. Masking for the surroundings is fixed depending on the installed position of each sensor, and only linear masking can be performed at a front end or a rear end.
Further, in a known inspecting device using a line image sensor, detection adjustment is performed by placing a defective sample on a stopped conveyor and confirming a detected level along a line. In practice, however, such detection adjustment may often malfunction because an image of a flowing cloth includes larger noises, which are caused by wrinkles, texture, etc., than those generated in a standstill state. In addition, such detection adjustment requires to be performed for each of defect types in cloths flowing on the conveyor. It is, however, difficult to determine a proper level and to accurately perform the detection for the reasons that even the same type defect as that in the defective sample does not appear constant when the conveyor including cloths passes, and that the conveyor is moved at a high speed.
Therefore, the applicant has previously proposed a cloth inspecting device comprising a conveyor mechanism, a rotation sensor for detecting a conveyance speed of a cloth, an illumination device, an input unit for picking up a line-form image of an inspection target portion of the cloth, a storage unit for storing, as two-dimensional image data, line-form image data from the input unit, a defect information storage unit for storing cloth defect information, a processing unit for determining a defect in the two-dimensional image data, which is stored in the storage unit, based on detection setting information that is input, and when the defect is detected, transmitting defect information to the defect information storage unit, and a folding-up unit including a plurality of cloth folding means disposed in the conveyor mechanism and discharge means for discharging the cloth to a predetermined location depending on the number of times of folding (i.e., the number of parts divided by folding), wherein the processing unit transmits the defect information to the folding-up unit, and the folding-up unit discharges the cloths in different numbers of times of folding based on the defect information from the processing unit (see Patent Document 3).
As one example of a method for inspecting a defective portion, such as a hole or dirt, which is generated in the surface of a sheet-like product made of cloth or paper, for example, there is proposed a method comprising the steps of arranging a plurality of inspection plates having surfaces in different colors side by side, moving the sheet-like product to pass over the surfaces of the inspection plates, and determining color changes which occur in the defective portion of the surface of the sheet-like product when passing over the inspection plates, thereby inspecting a defect in the surface of the sheet-like product (see Patent Document 4).
As one example of a device for inspecting a color difference in a sheet-like product by using a color sensor, there is proposed a device comprising a first CPU for controlling means which conveys the sheet-like product, an input unit for entering inspection conditions, a first display unit for displaying the inspection conditions, and controlling a first output unit for outputting initial conditions, three color sensors, and a second CPU for controlling the color sensors, a second display unit for displaying a detection result, and a second output unit for outputting the detection result, wherein the second CPU processes colorimetric data, which is obtained by the color sensors, to determine a color difference value with respect to a reference color value and a brightness deviation value, displays those values in real time on the second display unit in the form of graphs, and instructs the second output unit to print out the graphs at the end of inspection (see Patent Document 5).    Patent Document 1: Japanese Patent No. 3685522    Patent Document 2: Japanese Patent Laid-Open No. H8-276100    Patent Document 3: Japanese Patent No. 3813121    Patent Document 4: Japanese Patent Laid-Open No. 2000-329701    Patent Document 5: Japanese Patent Laid-Open No. H9-33348